DNA Test Links Snakebites to Species

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To treat victims of snakebites, it's important to know which type
of snake did the biting. Now, a new test looks at the tiny bits
of snake DNA that are left in the fang marks on victims, to
identify the species, a new study shows.

In the study, researchers collected 194 DNA samples from the bite
sites on snakebite victims in Nepal. In 21 cases, the patients
actually brought the dead
snake that had bitten them to the treatment center, and the
researchers were able to verify the source of the bite. In all of
those cases, the results of the DNA test agreed with the
dead-snake species identification conducted by independent
experts.

"You need to know the species that bit your patient [in order to
treat them]," said study co-author Ulrich Kuch, of the Department
of Tropical Medicine and Public Health at the Goethe University
Institute of Occupational, Social and Environmental Medicine in
Germany, and the developer of the snake DNA identification test.

Right now, the DNA test is too complex and time-consuming to be
performed for every snakebite victim, said study co-author
Francois Chappuis, chief of the division of tropical and
humanitarian medicine at Geneva University Hospitals in
Switzerland.

However, the test could be used as an epidemiological tool to
help doctors determine which snake species most commonly bite
people in different regions. [ The
World's 6 Deadliest Snakes ]

"When people get bitten by snakes, they rarely come to treatment
centers with the snakes" that bit them, so it is often not clear
which snake has inflicted a bite, Chappuis said.

In the new study, the researchers found that 87 of the 194 bites
were inflicted by
venomous species. The spectacled cobra was responsible for 42
bites, and the common krait inflicted 22 bites.

The new DNA test may also help researchers develop faster
diagnostic tests for snakebites, Kuch said. Indeed, the
researchers are working on developing a blood test that would
take only 20 minutes. Doctors could use this test to identify the
source of a bite, and more efficiently decide on the best course
of treatment, Kuch said.

For example, if krait venom were detected, doctors could quickly
administer antivenom instead of waiting for clinical signs of
envenomation,as they currently do, the researchers said.

In the study, the investigators also established a relationship
between the type of snake that inflicted a bite and the symptoms
that resulted from it. They found that krait bites happened more
frequently at night and indoors, while victims were sleeping.
They found that localized swelling tended to happen with cobra
and pit-viper bites.

The World Health Organization currently lists snakebites
as one of its 17 "neglected tropical diseases," which are the
conditions that cause a significant number of deaths and
illnesses but tend to get less attention from people in developed
countries.

Snakebite envenomation "affects the poorest of the poor," who
often live in regions where there is little awareness of the
issue, Kuch said.

"Most people are unaware that snakebite is a very real and
serious threat both to the health and economic vitality of rural
communities throughout much of the developing world," Dr. Alan J.
Magill, president of the American Society of Tropical Medicine
and Hygiene, who was not involved in the study, said in a
statement. "This innovative research may be enabling for the
development of a point-of-care test to positively identify biting
snakes."

The study was presented Tuesday (Nov. 4) at the American Society
of Tropical Medicine and Hygiene's annual meeting in New Orleans.
The results have not yet been published in a peer-reviewed
journal.